Screening of Castor Genotypes against Reniform Nematode under Microplot Condition

Reniform nematode (Rotylenchulus reniformis) is an important constraint in castor production, necessitating the identification of resistant genetic resources. The present investigation was conducted during the Kharif season of 2025 at Anand Agricultural University, Anand, Gujarat, to evaluate castor genotypes for their response to reniform nematode under microplot conditions. The experimental material comprised 19 entries, including the susceptible check GCH 7. Nematode infestation was assessed 60 days after sowing by staining the roots with acid fuchsin and examining them under a stereoscopic binocular microscope. Genotypes were classified according to the number of female nematodes per plant using the prescribed rating scale. Considerable variation was observed among the evaluated entries, with female counts ranging from 8 to 31 per plant among the parents and hybrids. NAUCI 1, SKI 315, 48-1 and SKI 215 were identified as resistant parental genotypes. Four hybrids, namely DCS 94 × SKI 315, JI 35 × 48-1, SI 8 × PCS 124 and ANDCI 1901 × NAUCI 1, also exhibited resistant reactions. In contrast, JI 512 × SKI 215 and the susceptible check GCH 7 were highly susceptible, recording 31 and 39 females per plant, respectively. These findings identify promising genetic resources for further validation and incorporation into castor breeding programmes targeting reniform nematode resistance.